Level-wind mechanism for magnetic recorders



G. o. HARM LEVEL-WIND MECHANISM FOR MAGNETIC RECORDERS Filed Aug. 22, 1944 Dec. 6, 1949 3 Sheets-Sheet l INVENTOR: GEORGE 0 HA RM BY Kw; flaw A TTOR N E Y5 Dec. 6, 1949 e. o. HARM LEVEL-WI ND MECHANISM FOR MAGNETIC RECORDERS 3 Sheets-Sheet 2- Filed Aug. 2.2, 1944 INVEN TOR:

I llllllllllHlllll iiiiiiiiiiiiil Illllllllli 5 650965 0. HARM A TTOR NE Y5 G. o. HARM Dec. 6, 1949 LEVEL-WIND MECHANISM FOR MAGNETIC RECORDERS 3 Sheets-Sheet 5 Filed Aug. 2 I944 um dllllll I INVENTOR:

650/?65 0. HA RM A TTOR NE YS Patented Dec. 6, 1949 LEVEL-WIN D MECHANISM FOR MAGNETIC accormsns George 0. Harm, Cleveland Heights, Ohio, as-

signor to The Brush- Development Company, Cleveland, Ohio, a corporation of Ohio Application August 22, 1944, Serial N0. 550,510

1 h This invention relates to magnetic recording and reproducing apparatus, and more particularly to apparatus utilizing a spirally-wound magnetic signal carrier, such as a tape or wire, for recording and reproducing signals.

' Among the objects of the invention are novel magnetic recording and reproducin devices of the foregoing type which overcome critical diffi culties heretofore encountered with such devices and which render their operation more foolproof and reliable.

The foregoing and other objects of the invention will be best understood from the following description of exemplifications thereof, reference being had to the accompanying drawings where-- in Fig. 1 is a top view showing in a general manner a recording-reproducing device exemplifying the invention, with the cover wall removed;

. Fig. 2 is a vertical cross-sectional view ofthe device shown in Fig. 1, along line 2-2 of Fig. 1; Figs. 3 and 4 are cross-sectional views along lines 33 and 4-4 of Fig. 2;

Fig. 5 is a partially-exploded diagrammatic view illustrating the general cooperative relationship of some of the elements of the device shown in Figs. 1 to 4; i

Fig. 5A is a diagrammatic view illustrating the reel mounting; v

Fig. 6 is a cross-sectional view of the magnetic head along-line 6.6 of Fig. 2; and g i Fig. '7 is a cross-sectional view of the magnetic transducer head along line 1-'! of Fig. 2.

The drawings show an exemplification of the invention as applied to a magnetic record track formed of a thin magnetic spirally-wound wire-' like filament II] which is stored, guided and im: pelled in its proper operating condition within a self-supporting detachable guide unit H designed for detachable interconnection with-"a driving or motor unit l2 which supplies the me-- chani'cal power required for impelling the magnetic signal carrier past a magnetic transducer head l3, the motor unit serving also to house the amplifier and the control elements for controlling the recording and reproducing operations. The magnetic head I3 is of a specialconstruction and will now be described in connection with Figs. 1 to 3 and 5 to 8.

It comprises a substantially rigid block-like .5 Claims. -(c1. I79100.2)

guide wall structure 2| which is shown suitably held on the top wall 14 of the motor unit 12. The upwardly projecting relatively narrow and elongated side of the guide wall structure 2| is arranged to form an outwardly opening elongated guide channel structure 23 having two winglike channel walls provided with outwardly tapering guide surfaces 24 extending from an elongated narrow channel track 25 formin the deepest region of the channel structure 23. The elongated narrow channel track 25 has a width of the order of the thickness of the wire filament Hi and is so designed as to serve as'a positive elongated guide surface which engagingly sup-' ports and guides a substantial length of the 'recording filament III as it moves through the transducing head I3.

The outwardly tapered guide surfaces 24 of the channel structure are so designed that a tensioned filament length which is biased toward the channel structure is automatically guided by the guide surfaces into positive guiding en-.. gagement with the long narrow channel track 25 forming the deepest part of the channel structure. The taper of the guide surfaces 24 is 'so designed and correlated to the shape of the narrow channel track as to cause a thickened filament element, such as a tie-knot joining two filament ends, to be lifted outwardly from the narrow channel track 25 and cause it to ride along outward regions of the tapered deflectingsurfaces 24 While moving through the transducer head l3. In addition, the taper of the guide surfaces 24 is such that they present to a wire protrusion deflected thereby a support which pre.

vents forces exerted by the tensioned moving.

wire from wedging "the wire protrusion withinthe narrow inward region of the channel.

Within the transducer head structure '21 is mounted a magnetic core structure havin two relatively thin pole pieces 26 ofhighly permeable magnetic sheet material which are longitudinally alined in a plane on the opposite sides of a marrow magnetic gap 21, the dimensions of which are shown exaggerated for the sake of clarity, but which is only about .001 inch. The two aligned pole pieces 26 are so held clamped within the blocklike structure 2| of the magnetic head l3 as to expose along an intermediate portion of the channel structure the two narrow pole faces 28 bordering the narrow gap 21 for tangentially engaging a wire filament guided in positive engagement along the channel track 25 of the transducer head.

The two pole pieces 26 are shown united to a common mounting ring 29 and are arranged to complete a magnetic circuit with a yoke member 3| of highly permeable magnetic material which is surrounded by a transducer winding coil 32. The wall structure 2| has formed therein a. laterally-facing generally-circular cavity exposing in the interior a surface shaped for receiving and holding'in a properly aligned operating position the double-pole-piece unit with the two pole pieces as well as the yoke member 3|,

with its transducing coil 32 in the manner indicated in Fig. 6.

The double-pole-piece unit associated with the mounting ring 29 of the transducer head is shown held in its proper operative position within thecavity of the wall structure 2| by a cover member 34 which is afi'ixed to the wall structure as by two screws 35. The magnetic "head 13 is also equipped with electromagnetic obliterating means of obliterating all previous magnetic recordson each element of the signal carrier filament. moving toward the gap region 27 of the two transducer'head pole pieces 26.

The obliterating means are shown formed of a substantially closed magnetic core structure 3% and a winding coil 31 surrounding the core. One side of the core structure 35' is provided with a gap region 38 crossing a portion of the channel track 25 so that each element of the signal carrierfilament [0 moving in the direction of the arrow ill-l has to pass through the'gap region38 of the obliterating core structure 36 on which all the previous magnetic recordings are obliterated before each element of the signal carrier is brought to the gap region of the transducer head pole pieces 26. The obliterating core structure 36 and its winding31'are so designed that when the windingis excited by suitable obliterating current, either A. C. or D. C., a strong obliterating flux will be produced in the gapregion 38 of a magnitude suificient to obliteratev all previous magnetic records 'oneach signal carrier element passing therethrough and bring it to a uniform condition.

The wire in is shown stored in spirally-coiled form on two reels M, 42 which are shown mounted on two revolvably mounted shafts 43, 44 which are revolvably supported in the detachable guide unit ii. The guide unit comprises a holder structure formed of a casing having a lower cas ing wall member 45 and an upper casing wall member 41 suitably secured to each other as by screws, not shown, extending'through suitably thickened wall portions of the casing. Amounting wall 48 or plate is supported at a suitable level above the lower'casing wall member 45 and secured thereto, as by four spacer rods "49, the ends of which are suitably fastened, as by'ri-vet and screw joints, to the two wall members '45, 48.

The two ends of each of the two reel shafts 43, 44 are rotatably mounted in bearing'me'mbers, such as Oilite-type; self-lubricating bearing memberssuitably held in holes of thebottom wall 45 and the mounting wall 48.

The reel holder unit is designed for easy de-' tachable coupling in the properly aligned position t0"the separate motor unit. The motor unit I2'is shown provided along its upwardly facing coupling wall M with two aligning pins 5i interfitting with corresponding aligning holes formed 4 in the bottom wall 45 of the reel holder structure. The reel holder is automatically locked in the aligned coupled position by two spring arm latches 52 suitably secured to the side walls of the motor unit I2 and having latch projections 53 which overlie and interlockingly engage underlying edge portions of the bottom wall which are exposed through cutouts provided in the end walls of the casing structure 41. The upper face of each latch projection 53 is tapered so that when the reel holder is pushed downwardly into its aligned position on the .motor unit, the two latches "52;.arepushed outwardly and then automatically returned by their spring arms to their .inward latched position when the guide unit is brought to its downward coupled position shown in'Figs. 2 to '4.

. The motor unit is provided with two reel driving shafts-43e-l, 44-l suitably mounted therein so that when .the reel holder II is placed in its shafts ,43,- .4, respectively.

ill

The intercoupling portions of the lower ends of the reel shafts 43, 44 and the v.upper-endsiof thedriving shafts 43-I, 44'l, areof the selfcentering type. The driving "shafts 43l 44'-l are designed to embody suflicient self-restoring yieldability so as to assure that when the reel holder unit H is coupled to the motor unit l2 the cooperating shaft ends 43, 43-l, 44, 44| are automatically centered and brought into coupling engagement. Inthe arrangement shown, the upper ends of each driving shaft 43-l, 44| are connected to the main body of the shaft through an elastically yieldable member, such as a'bellows-like metal sleeve 54 and the upper end of eachclriving shaft 'isprovided with a grooved or splined periphery'and a pointed tip so as to enter and establish positive coupling engagement between its grooved exterior and the corresponding grooved "interior hole formed on the lower ends of the two reel shafts 43, 44.

The two ends of the coiled wire are suitably fastened to the"inner'coresof the two reels 4|, 42' and the guide arrangement is of such character as to assure that the length of wire passing through the transducing head I3 is at all times under tension. In Fig; 5A is shown one simple manner for assuring that the wire is at'all times under tension.

As shown, one of the reels, namely, in the arrangement'shown, reel 4|, which is intended to be rotated clockwise for winding thereon the wire during a recording or reproducing operation, is shown aifixed to its shaft 43 asby a key 55, the other reel "42 being interconnected to the shaft through elastically yieldableenergy storing means in the formof a'spirally-coiledspring 56 interconnected between the core of 'the "reel 42 and a c'ollar5lfof the shaft 44.

The two "reels are mechanically connected to each other IlOtiODlY by the length of' wire 1 0 extending between thetwo reels but also by an additional positive motion-transmitting means indicated in Fig. 5A by'a'series of interengaging, rotatably-mounted gears 58', 58-4, 582, 583, 58-4,'which,"as indicated in Fig. 5A, may be housed in the compartmentof the'cover wall 41.

A spirally-wound flat spring of the type used in alarm clocks, but of non-magnetic metal, may be usedas' the biasing spring 56 and it is so designed that when the entire length-of the wire, except for the end anchoredon-reel 4|, is wound thereon cause it to move with increasing peripheral velocity and cause the reel 42 from which the wire is being unwound to turn at increasing speeds.

In order to properly record with a wire stored in spirally-coiled form on the reels, it is essential that the wire is properly distributed in level layers while it is being wound on one reel from.

the other. In accordance with the invention, the up-and-down oscillatory motion is imparted to the wire as it is being wound from one reel to the other by a special level-winding structure which is, shown formed by a substantially rigid channel frame member 6| having one side 62 lonigtudinally aligned on the side of the two reels along which the magnetic head I3 is located, the other side 63 of the channel structure 6| being provided with two channel sections 64, 64-4 of a crosssection indicated in Fig. 4 providing an outwardly facing guide channel track 65 along which the length of wire Ill-5 leading, for instance, from reel 4!, is guided first over the arcuate channel track of the channel section 64-l toward the channel track of the transducer head and led therefrom over the channel track 65 of the channel section 64 to the spool body of reel 42.

The channel structure mounted, as by pivot brackets 61 secured to the bottom wall of the holder structure engaging pivot protrusions 68 of the channel structure which are so arranged that the channel track portion extending along the side of the channel structure aligned opposite the transducer head guides the wire and passes it toward the bottom region of the deepest channel track region 25 of the wing-like transducer head structure.

In order to assure that the wire is subjected at all times to the biasing action in the direction into engagement with the channel track 25 of the transducer head, there are alsoshown provided two additional biasing arms'll having a downwardly facing channel portion 12 engaging the upper side of portions of the wire [0 moving away and toward the channel track 25 of the transducer head in the manner indicated in Fig. 3, the two arms H being suitably secured, as by screws 13, to the bottom wall 45 of the holder structure.

The pivot supports 6'! for the level-winding structure 6| are so arranged as to make it possible to oscillate its side 63 up and down for causing the wire to be distributed helically, layer upon layer, while assuring that the portion of the wire which moves past the transducing head is not disturbed by the oscillatory motion by reason of the fact that a long portion of the moving wire is engaging the channel tracks 65 of the level-Winding channel structure on the way toward and away from the transducer head.

The up-and-down oscillatory motion around the pivots 51 is shown imparted to the levelwinding structure 6! by an endless screw 13 having its ends suitably journalled in the bottom wall member 45 and the mounting plate 48 of the holder structure, the threads of the levelwinding screw serving to impart an oscillatory up-and-down motion to a claw nut 14 which is is shown pivotally 5 6 shown flexibly connected, as by pivot pins 15 and a mounting bracket '16, with the side 63 of the level-winding structure 6| extending on the side opposite the side on which it is pivotally supported.

As shown in Figs. 1 and 3, the mounting bracket 16 is suitably afiixed over an opening in the wall portion of the side 63 of the level-winding structure 6| and the upper end of the level-winding screw 13 is driven at a suitably reduced speed by a reduction gearing located in the compartment enclosed by the cover wall 41 so that the oscillatory wire leveling operation is suitably correlated to the rate at which the wire is wound on one or the other of the reels. The features involving the combination of a detachable reel holder unit designed for cooperation with a drive unit on which the magnetic transducer head is supported and arranged so that when the reel holder unit is coupled to the motor unit the magnetic record track is automatically brought into operative engagement with the transducer head, are not part of the present invention but are claimed in the application of.S. J. Begun, Ser. No. 550,572 filed August 22, 1944, now abandoned. The magnetic recording devices described herein to exemplify a form of the present invention embody various other inventive features which are claimed in applications Ser. No. 550,571 filed August 22, 1944, Serial No. 687,046 filed July 30, 1946 and Serial No. 688,738 filed August 6, 1946, all assigned to the assignee of the present application.

It will be apparent to those skilled in the art that the novel principles of the invention disclosed herein in connection with specific exemplifications thereof will suggest various other modifications and applications of the same. It is accordingly desired that in construing the breadth of the appended claims they shall not be limited to the specific exemplifications of the invention described herein.

I claim:

1. In a magnetic record transducing arrangement for transducing magnetic records, such as recording or reproducing magnetic signals, by magnetic flux interlinkage between a track element of a moving magnetic record track and a relatively fixed magnetic record transducer head including windings carrying electric signals corresponding to the magnetic records: two revolvably mounted reels and a record track arranged to form two coils held on said two reels and an intermediate track portion extending between said coils so that when said track is wound on one reel it is unwound from the other reel; said reels forming part of storing means including guide means and impelling means for guiding and impelling an intermediate track portion of said record track extending between said reels along a predetermined path past said transducer head; said guide-means including a guide structure engaging and guiding said intermediate rv track portion and holding a portion thereof passing through said transducer head at a substantially fixed level relatively to the pole faces of said transducer head; and means for imparting toa portion of said guide structure reciprocatory movement for causing it to level wind the record trackon the reel on which it is being reeled; said guide structure including a unitary relatively rigid member comprising unitary spaced guide portions engaged by portions of the track leading from each of said two reels, for holding a section cf the intermediate "track "portion exposed for engagement with the transducing head.

ing to the magnetic records: two laterally-spaced revolvably-mounted reels and a record track ar- "ranged to form two coils held on said two reels and an intermediate track portion extending between said coils so that when said track is'woun'd on one reel it is unwound from the other reel; said reels forming part of storing means including guide means and impelling means for guiding and impelling an intermediate track portion of said record tracka'long a predetermined path past said signal transducer structure; said guide means including 'a guide structure engaging and guiding said intermediate track portion and holding a portion thereof passing through said transducer head in aisubstantially fixed position relatively to the pole faces of said magnetic transducer head; and means for imparting to a portion of said guide structure reciprocatory movement foricausing it to level wind the record track on which it is being reeled; said guide structure including a unitary relatively rigid guide member mounted 'for pivotal movement about an axis generally parallel to a plane through the axes of the two reels and having r'spaced guide portions engaged by portions of the track leading from each of said two reels, said guide portions holding a section of the intermediate track portion exposed for an engagement with a transducing head.

'3. In a magnetic record transducing arrangement for transducing magnetic records, such as recording or reproducing magnetic signals, by magnetic flux interlinkage between a track element of a moving magnetic record track and a relatively fixed magnetic record transducer head lincluding windings carrying electric signals corresponding to the magnetic records: two revolvably mounted reels and a record track arranged to form two coils held on said two reels and an intermediate track portion extending between said coils so that when said track is wound-on one reel it is unwound from the other reel; said reels forming part of storing means including guide means and impelling means .for guiding and impelling an intermediate track portion of said reoord track extending between said reels along'a I predetermined path past said transducer head; said guide means including a guide structure engaging and guiding said intermediate track portion and holding a portion thereof passing through said transducer head at a substantially fixed level relatively to the :pole faces of said transducer head; and means for imparting-to. a portion of said guide structure reciprocatory movement for causing it tor-level wind-the record track on the reel on which it is being reeled; said guide structure including a substantially rigid guide member for guiding a length of said record track around the circumference of at least one of said reels.

4. In a magnetic record transducing arrange ment for transducing magnetic records, such as recording or reproducing magnetic signals, by magnetic flux interlinkage between a track element of a moving magnetic record track and a relatively fixed'magnetic record transducer head "including windings carrying-electric signals 'c'or- 'respondingto the magnetic records-z two revolvably mounted reels and a record track arranged to form two coils held 'on said two reels and an intermediate track portion extending between said coils so that when said track is wound on one re'e'l it is unwound from the other reel; said reels forming part of storing means including guide means and impelling means for guiding and impelling an intermediate track portion of said record track extending between said reels along a predetermined path past said transducer head; said guide means includinga guide structure engaging and guiding said intermediate track portion and holding a portion thereof passing through said transducer head at a substantially fixed level relatively to the pole faces of said transducer head; and means-for imparting to a portion of "said guide structure r'eciproca'tory movement for causing it to level wind the record track on the reel on which it is being reeled; said guide structure including substantially rigid guide member elements 'for g-ui'ding portions of said record track "around the circumference of said two reels.

5. In a magnetic record tra'nsducing arrangement for transducingmagnetic records, such as recording or reproducing magnetic signals, by magnetic flux interlinkage between a track element of a moving magnetic-record track and a relatively fixed magnetic transducer head including windings carrying electric signals corresponding to the magnetic records: two laterallyspaced revolvably mounted reels and a record track arranged to form two "coils held on said two reels and an intermediate track portion extending between said coils so that when said track is wound on one reel it is unwound from the other reel; said reels forming part of storing means including guide means and impelling means for guiding and impelling an intermediate track por- "tion of said record track along a predetermined path past said signal transducer structure; and guide means including a guide structure engaging and guiding said intermediate track portion and holding a portion thereof passing through said transducer head in a substantially fixed position relatively to the pole faces of said magnetic transducer head; and means for imparting to a. portion of said guide structure reciprocatory movement for causing it to level wind the record track on the reel on which it is being reeled; said guide structure including a substantially rigid guide member for guiding a length of said record track around the circumference of at least one of said reels.

6. In a magnetic record transducing arrangement for transducing magnetic records, such as recording or reproducing magnetic signals, by magnetic flux interlinkage between a track element of a moving magnetic record track and a relatively fixed magnetic transducer head including windings carrying electric signals corresponding to the magnetic record's: 'two laterally-spaced revolvably mounted reels and a record track arranged to form two coils held onsaid two reels and an intermediate track portion extending between said coils so that when said track is wound on one reel it is unwound from the other reel; said reels forming part of storing means including guide means and impelling means for guiding and impelling an intermediate track portion of said record track along a predetermined path past said signal transducer structure; said guide means including a guide structure engaging and guiding said intermediate track portion 9 10 and holding a portion thereof passing through said transducer head in a substantially fixed REFERENCES CITED position relatively to the pole faces of said mag- The following e e e ces are of record in the netic transducer head; and means for imparting file of this patent:

to a portion of said guide structure reciprocatory UNITED STATES PATENTS movement for causing it to level wind the record track on the reel on which it is being reeled; Number Name Date said guide structure including substantially rigid 773,935 RieS Nov. 1, 1904 guide member elements for guiding portions of 909,414 Hytten Jan. 12, 1909 said record track around the circumference of n 1,123,147 Sherman Dec. 29, 1914 said two ree1s 1,237,496 Frankhauser Aug. 21, 1917 1, 13,40 Lebeis Oct. 28, 1924 GEORGE O. HARM. ,9 Knapp Oct. 22, 1946 

